Lap



' BOY B. FEIER, O]? DETROIT, MICHIGAN, ASSIGNOR, BY MESNE ASSIGNMENTS, T DE'IROIT Patented Nov. 15, 1932 UNITED STATES PATENT OFFICE TRUS'J. COMPANY, OF DE'1ROIT, MICHIGAN, A CORPORATION OF MICHIGAN LAI Application mm April 17,

This invention relates t0 the art of manufacturing gears, and more particularly to the means usecl in the method of forming re; lieved areas in the teeth of the gears disclosed in my copending application Serial N0. 523746fi1ed Max. 19,1931.

In my copending method application I have disclosed gears in which the initial engagement of the mating gear teeth is delayed t0 the region of the pitch line without altering the engagement of the teeth during their recess action in order that the noises resulting from impacting engagement may be materially reduced, with the result that a set of gears built in accorclance with my invention Will be pract-ically silent in koperation under ligl1t 01' hea.vy loadp As disclosed in the copencling application referred to, this non-impacting result is obtained by forrning areas ofrelief in the active faces o:f the gear teeth. In one case this action'may' be accomplished by relieving the addendum faces' 0f the driven sides of all driven teeth from th e tips of the teeth t0 theregion 0f the pitch line, ancl in another case, this action may be obtained by relieving the declenclum faces of the driving sides 0f all driving teeth. The object in both cases, however, is to pro-viele a set ofgears in which the driving engagement occurs mainly during the angle of recess.

In my copending methocl application I have clescribed a method of lapping gear teeth which enables the relievecl areas t0 be obtained. ancl this application relates to the means that may be used in the niethod 0f forming the relievecl areas on the addendum faces of the drive1i sides 0f the gear teeth.

I1; is one of the objects of the present invention to provide a lap f0r gears and the like aclapted :for use in forming an area 0f relief in the adclenclum faces of the driven sicles of gear teeth in orcler 130 obtain the improved qear tooth action referred t0.

Anot-her objebt is to provide a lap f0r gears ancl the like of suchconstruction th at it may form an area of relief in the addenclum faCes of the driven sides of gear teeth ancl at the Same time may lap the dedelidllm fa :es Of such sicles.

1931. Serial N0. 530,784.

Another object is t0 provide a lap for gears and the like of sucliconstr'uction Which in cooperative action with the gear teeth Will remove an amount of metal from one surface of each foothgreater than the amount of metal from another surface thereof.

A further object is t0 provide a lap fr gears ancl thelike arranged to have a greater lapping or abrasive action on the addendum faces 0f the driven sides of the gear teeth than 0n ehe dedendum faces of the drivn sicles of tl1e gear teth.

' With the above and other objects in view Which will be appa rent from tha detailed following cleScription, the present invention consists in c'rtain features of Construction and combinations of part s that will be reaclily understood by Chose skilled the.art t0 Which the invntion appertains.

In thedrawings, Which illustrate suitable embodi'ments of the invention5 F igur 1 is a diagrarhmatic view showing the c0nbo1 0f the gear tooth in which th'e adderidum face ofits clriven' sid'eis relieved abruptly at the pitch line and c01'1tinuing t0 the tip of the t-ooth, the dotted lines representing th original pf0file of the tooth befor th'e relief is formed;

Fig. 2 is a diagrzimmatic view showing the -c0ntour of a gear tooth haVing its addenclum face 0n its driven side formed with a relief which .gradually fades out t0 zero near the pitch line, between the pitch line and thetip 0:E the footh, the dotted line representing the original profile of the t0-oth before the relief is forme Fig. 8 is a side elevation of one type of lap tl1at may be used in forming' the v relief shown in Fig. 2, aportion ofthe, lap being broken away t0 Show the same in longitudinal section;

Fig. 4 is an enlarged transverse section taken substantieilly on the line 44 of Fig. 3;

Fig. 5 is a longitudinal section 01 anot-her type 0f lap that may be used in fornmng the relief of Fig. 1 and for lapping the dedenclum faces of thedriven sides of the tooth a1: the same time;

Fig. 6 is an enlarged'sectiontaken substantially 011 li1ie 66 o:f Fig. 5;

one illustrsited in F ig. 1, the

gear and lap are registered with each other,

and then a sufficient continuous ancl resilient pressure is I3e imparted to both the gear and 1ap. Dur

mg the reciprocation the pressure is continuously and resiliently exerted a szainst the gear teeth by the lap, and as a, result of this rela tive reciprocation, the lap teeth 16, as well 21s thG addendum faces ad f the gear teeth,

will be gradually worn down by the abrasive action, with the result that .the substantial relief 12 may be formed, und it Will be noted that because 01 the short dept-h 0f the 1ap tooth 16, the relief Will be abrupt atthe pitch line, as indicated in Fig. 1.

If it is desired to form the relief 12 in such a manner that-the reliefs will be uniformin contour and be equi-spaced, the gear andlap may be rotated relative t0 each other When they a1e out of registration to obtain a different registration of the 1ap teeth with t-he gear teeth'and this 1nay be, as outlined in the .lapping process, tooth-by-tooth, 01 it may be at any desired number of teeth. In any eveut, however, a suffic1ent number of relat1ve IGC1} rocat-1ons are unparted to the gear und lap to cause a. wearin awa of the metal 011 the ac1- dendum faces acl of the driven sides 0f the gear teeth 11. 4

After the reliefs are formed in the addendum faces of the driven sides of the gear teeth, the dedendum faces -may be further lapped in accorda1ice with the process previously described, er, if desired, these dedenclum faces may be lapped before the addendum relief is formed. The opposite faces 0f the teeth may also be lapped, if desired.

In cases Whe1e the gear may acta as either a. driven 01 driving gear,but always in the same direct-ion of rotation, it may be desirable t0 form the addendum relief in the side that is ordinarily the driven side and with the same lap after 01 before the relief is 1apped in, so 1ap in accordance with the lapping process descr ibed the opposite sides 0I" y the teeth Which may become the driving sides.

In this case I prefer to use a lap having teeth 23 of the type shown in Fig. 11. It Will be noted in this tooth 23 that the one face portion of the 1ap tooth lying radially inwardly of the pitch circle is cut away at 24, so that during lapping the remaining face portion Will lap in t11e abrupt relief 12 of 1 W11'-11- out lapping the dedendum face 01 thetooth. This provides a lap in Which the opposite side 0f the lap tooth may be used 0.com1letely 1ap the side of the tooth of the gear which may become the driving side.

In other cases, however, it may be desin ab1e in forming the addendum relief of Fig; 1 in the driven sides ofthe driven teeth while lapping the dedenduni faces thereof. In this case I pref'er t0 use the type of lap shown in Figs. 5, 6 and 7. In the lap 17 illustratedin these vievvs, it will be noted that the portions 0f the 1ap teeth 18 lying radially outwardly construction as shovvn in Fig. 3, but that the teeth are also formed ab their central portions intermediate their ends to 11111 depth, as 1ndicated in Fig. that is, theyare formed with a centra1 portion 19 extending'radially inwardly of the pitch circle. In other words, the central portion 1901 eachlap t00th18 is formed to full depth, so tha such central portion 19 Will be complementary to the entire face (0cle 'of the tooth t0 be lapped, und that the ends of euch lap tooth 18 adjacent the central portion 19 are cut 011 at the' pitch 1ine to provide end portions; Which are complementary only to the addendum faced of the tooth to be laPped. I/Vhen a 1ap a 0f this character is used in co nnection with a gear to be lapped, the 1ap teeth Will lap the dedendum faces cle of ehe gear teeth, und at the same ti1ne will 1ap und form the reu". 0f the pitch circle are of the same general lief 0f the type 12 shown in Fig. 1 in Ehe addendum faces of the sicles 0f the g6ar teeth Wh1(lh are ;t0 be the driven sides thereof.

Th1S result is produced by reason of the fact that during relative reciprocations of the gear and lap, the lap teeth throughout agiven stroke will have a louger period of contact with the addendum facesacl 0f: the'gear teeth than with the dedendum .face's d'e of the gear te6th, with the result that there Will be a, greater wearing-away 0f the addendum faces ad than o f the dedendum faces cZ-e ofthe driven sides 0f the teeth. This action is clearly obviousbecause it will be noted that the narrow radially invvarcl portious 19 of the lap teeth, which are of uniform length, Will have full contact with the faces of the teeth 0f the gear, und that the radially outward portions of, the lap teeth Will ha ve contact with only the addendulh faces a*cZ of the sides of the teeth that are t0 be the driven sides when in operation. IVhen a lap 0f this character is used the process may be carried out in the manner previously described, it being understood, of course, that during the lapping proce'ss a resilient torque is continuously exerted by the lap against the teeth of the gear being lapped.

In case it is desired t0 form the gradual relief 141 in the gear teeth on the addendum faces ad of the driven sic1es thereof, as indicated in Fig. 2, I prefer to use zvlap 0f the character indi'cated in Figs. 8 and 9. The 1ap in thiscase will lap the dedendum und al's0as showninFi'g. 5. In this laphow ever, the encl portions Of e;ehtooth 21 are' nc; t unifotmly cut off tt-thepitch 'c'irclet'o the1r pitch line substantiallytthe terminzitions f-the ce1itralpottion-2Q of 'the lap teeth in such-a manner that the 'circuniferential facescf ehe Guter encls of=the lap teeth terminate neaily coinciclelit -Wili tl1e inner circ mnferenti alface of'the'la'p at the extmmities ofthe-tee'th. In cther words, lt Will be notecl that theraclially ou't'war'cl end p'0itions o'f the en'cls of*the lap are ap'proache'cl, Will cause a graclualWveari'ng-awaycf metal from the pitch line gratlually 0Ve'r'the adclendum face acl toWa'rcl the' tip of'the teeth, sothat, as aie'sult, the graduzil -aclclenclumrelief I4- 011 die Sicles cfthegea'r teetlrwhich becomethe clri'ven sicles Will'be formed and'that this-relief;will be alsa maximum a't the tip 0f the tjooth and will gra'duzilly fade 0ut substantially at thepitf'ch circle. In 'case, however, tl1t it is d'esirecl tdhz1veth'e gr-a'dual relie;f f&cle ont"befiween"the tip oii-the"toth ancl'the pitch cifcle of tliegeztr,it is'0bVious than with o thi-s par'biculaf-Wpe of lap such a condition can be obt-aine'd bymerely 'forming the outer porticns cf the lap tooth so" that they merge with the central poftion cf the l ap tooth ia'diall'y outward of the pitch circle.

Inusing the la'p 20 in connedtion with a- *gear in which it is clesirecl t0 form a graclual relief 011 tl1e acltlendum faces cf the sicles cf the gear'teeth which are t0 be t he driven sides -thereof ehe gear and lap are given the clesirecl number 0f reciproczitions relative to each other while the lap is subjectecl to a resilient torque, ancl when it is clesired to have a uniformity of tootl1 contours ancl t00th spacing the gear and lap may be rotatecl relative t0 ea ih other t0 charlge fhe registration cf the teeth in the same manne'r as previously describecl.

In che ca'se'0fa gear which is -used in indust1i2il practice where the clriven'gear is-always the driven gar and. 11eve1 becomes the driver,

and is zilso arrangedo 0petziteinopposite clirectionsit mayb'ede'sirable, as described in my copendirigupplicationto form the relief on b0thadclen'clumT-aces cf the driven sicles of the -geanteeth, sinceboth sicles may be t'he driven sid'e. In this case the laps shoWnin the drawings may be used 130 form the relief 011 the oppositeaclclenclum faces, the only change in the process necessary being that, after the addendum faces on one sicle of the gear teeth are lapped the direction ofresilient pressure createcl by tl1e lap is reversed, so that the lap teeth will bear against the opposite sicles f ehe gearteeth und forma the relief in the addendnm faces thereof.

lt is so be unclerst'ood that in the lapsillustraced in Figures 5 and 8 itis not necessary tha't the entire portion lying radially inward cf the pitch circle be completely cut away,

but tha't the dkasirecl results may be obtained by mexely cutti'ng out the faces of such portio'n's in suchamanner as to render them ineifective.

In Figure 10 I have shown on'e ofthe relativepositions tha't a gearand lap assume during the lapping proc'ess.

I1; 'is to be observed from' the clrawings and foregoing description that, in the laps describedeach lap has the portions that lie radially inwa'rclly cf -ehe pitch circle either partially o'r compleely cut away und rend-erecl inefiective, to produce the desired results, that is the formation in all cases cf an ad'dendum relief ancl in some cases' the'for'mation of such relief without altering the selected pr0file ofthe dedenclum faces.

The laps of Ehe present invention are very aclva;ntageous in"thals gear teeth maybe cut With the conventio'nal cutters t0 their desired profile and 'the'n th e relif may be fornied in -1ihe desirecl addendurn faces of c-he driven sides thereof in a separate operatio'n in a very eflicient manner, with theresult that such relief can be 'moreeconomically obtained 'with a savingin cost, since the cutters ancl the like which would necessarily have to be of a modifiecl non-conventional type, would cc'st 0011- si'derably more than the cst cf conventional cutters ancl laps cf the present invention.

Another aclvantage which is readily apparent, is that the gear teethcan be very efficiently f0rn1ed with reliefs therein and 'at the same 'time they may be very efliciently lapped in accordance wich the process described.

Itis to be understoocl that=the term faces, where usecl in the claims, is t-0 be construed as the faces of -the lap teeth that are complementary to the teeth of the gear to be lapped.

Although I. have shown und clescribed the present invention as being applicable to the l apping cf external gears, it v is understood thatfche same may be used in connection with laps for lapping internal gears,

Furthermore, it is 130 be undcrstood that the particular forms of apparatus shown and described, and the particrilar procedure set forth, are presented forpurposes of explanation and illustration and that various modifioations 0f said apparatus and procedure can be made without departing from my in vention as defined in the appended claims. What I claim is:

1. An annular lap having a series of internal lap teeth arranged around the inner circumfrential face thereof substantially complementary to the teeth of a given gear tobe lapped, each extending continuously from one end 0f the lap to the other, and each having the ortion thereof extending radially inwardly from the pitch circle partially 0r completely removed, whereby the portion outwardly of the pitch circle may form an area of relief in the addendum face of the driven side of the complementary tooth of the given gear t0 be lapped.

2. An annular lap having a series of internal lap teeth arranged around the inner circumferential face thereof substantially complementary to the teeth of a given gear t0 be lapped, eaoh extending continuously from one end of the lap to the other, at least one of the faces of each tooth having the face portion thereof lying radially inwardly of the pitch circle partially 01 completely ineffective With respeot t0 the lapping of the dedendurn face of the driven side of the complementary tooth of the gear, wherebythe effective face portion of the said lap tooth may forn1 an area of relief in the addendum face of the said driven side of the complementary gear tooth.

3. An annular lap having a Series 0f longitudinally extending internal lap teeth arranged oomplementary to the teeth of a given gear to be lapped, at least one of the faces of eaoh lap tooth having the portion thereof lying radially outwardly of the pitoh circle of greater area than the remaining face portion thereof, the san1e remaining face ortion from the pitch line radially inwardly to the tip thereof being of substantially uniform longitudinal lengtl1, wherebv,

. during relative reciprocation of the gear and lap, the radial'ly inward face portions of the lap teeth may lap the dedendum faces ofthe driven sides of the gear teeth and simultaneously the radially outward face portions of the lap teeth may form areas of relief in the addendum faces of the driven sides of the gear teeth.

4. An annular lap having a series of longitudinally extending internal lap teeth arranged complement-ary t0 the teeth of a given gear t0 be lapped, a least one 0f the faces of eaoh lap tooth having the portion thereof lying radially outwardly of the pitch circle of greater area than the remaining face portion thereof, the said remaining face portion from the pitch line radially inend of said lap whereby,

wardly to the tip thereof beifig bf substantially uniform longitudinal length, and the said radially outwardface portion from the pitch line radially outwardly substantially t0 the base thereof being of substantially uniform length, whereby, during relative recipv rocation of the gear and lap, the radially inwardface portions 0f the lap teeth may lap.

the dedendum fades 0f the driven sides of the gear teeth and simultaneously the radially outward face portions of the lap teeth may form areas of relief in the mdclendrim faces each lap tooth having the portion thereoff lying radially outwardly of the pitoh circle of greater area than the remaining face portion thereof, the said remaining face portion fromthe pitch line radially inwardly t0 the tip thereof being of uniformlongitudinal length, andsaid radially outward face portion being of gradually decreasing area from the radially inward portion toward the end of said lap reciprocation ofthe gear and lap, the radially inward face portions of the lap teeth may lap the dedendum'faces of the driven sides of the gear teeth and simultaneously the radiallyoutward face p01tions ofthe lap teeth may form areas 0f gradual relief in the addendum faoes ofthe driven sides of the gear teeth.

6. An annularlap having a series of longitudinally extending internal lap teeth arranged complernentary to the teeth of a given gearto belapped, at least one of the faces of each lap tooth having the portion lying radially outwardly of the pitc h circle of greater area than the remaining face 'portion thereof, the said' remaining face portion teeth, whereby, during relative from the pitch line radiallyinward to the tip thereof bieing of uniform longitudinal length and the said radially outward face portion being of maximum depth adjacent the radially inward portion and of gradually de creasingdepth as said tooth approaches the during relative reciprooation of the gear and lapthe radially iriward face portions of the lap teeth may lap the dedenclum faces of the 'driven sides of the given gear and Simultaneously the radially outward face portions of the lap teeth may form areas o f gradual relief in the addendum faces of the driven sides of the gear teeth. v

7. An annular lap having a series 0f longitudinally extending internal lap teeth arranged complementary to the addendum faces of the teeth of a given gear, said teeth being of uniform longitudinal length' and 

